Although there's no way to be sure, I would guess that she dislikes him for being illegitimate, and therefore disgracing the family （and of course that's not even remotely his fault）. And beyond that point, she must have blamed Tamaki further for making his existence known rather than staying in France, and proceeding to inherent the company, something an illegitimate son doesn't seem to "deserve". So essentially, his grandmother resents him for being the 来源 of a 《丑闻》 and regrets that he is not treated as exactly that.
posted 一年多以前
Ah, I see now and that makes plenty of sense too. So thanks for the explaination
